Borosilicate luminescent material and preparing method thereof

ABSTRACT

Provided are a luminescent material and a preparing method thereof. The borosilicate luminescent material has a chemical formula of aM 2 O.bLn 2 O 3 .cAl 2 O 3 .dR 2 O 3 .eSiO 2 .fCeO 2 .gTb 2 O 3  or aMO.bLn 2 O 3 .cAl 2 O 3 .dR 2 O 3 .eSiO 2 .fCeO 2 .gTb 2 O 3 , wherein M is alkaline earth metal or alkali metal, Ln is one or two elements selected from the group consisting of elements Y and Gd; R is one or two elements selected from the group consisting of elements B and P; a, b, c, d, e, f, and g are molar fractions, and 6≦a≦20, 3≦b≦12, 20≦c≦30, 32≦d≦45, 0≦e≦12, 0.01≦f≦1, and 0.05≦g≦1.5. The preparing methods comprises the following steps: 1) selecting source compounds of above elements; 2) mixing and grinding the source compounds to obtain a mixture; 3) presintering the mixture, then grinding the mixture; 4) sintering under reducing atmosphere, and cooling, thereby obtaining the luminescent material.

FIELD OF THE INVENTION

The present disclosure relates to luminescent materials, especially to a borosilicate luminescent material and a preparing method thereof.

BACKGROUND OF THE INVENTION

With the breakthrough in the third generation of semiconductor material gallium nitride, and the advent of blue, green, white light emitting diode (LED), LED, which have a reputation for being the technology to illuminate the future, is walking into our lives and will guide us to illuminating light source. LED light source is a kind of new generation of light source. Primarily, a white LED can be obtained by the following methods: 1. coordinating blue LED with yellow fluorescence powder to produce white light; 2. encapsulating chips of different chromatic lights to produce white light by mixing different chromatic lights; and 3. excitation tricolor fluorescence powders by ultraviolet LED to produce white light.

At present, from the point of technology and application, white LED on the market is the white LED obtained by coordinating blue LED with yellow fluorescence powder. Because the white LED mainly contains blue light and lacks red light which presents a cool color, and color rendering index is lower, the application area of it is greatly limited. Encapsulating chips of different chromatic lights is provided. There are many disadvantages in practical promotion because the driver circuits of chips are complicated. Excitation tricolor fluorescence powders by using ultraviolet LED, producing white light by mixing different chromatic lights, can obtain LED light source with higher color rendering index, which is research hotspot. In tricolor fluorescence powders, green fluorescence powder with high luminous efficiency is used as sulfide fluorescence material, which has the problem that stability is not high enough. LED chips have an advantage of long lifespan, however, the lifespan of LED light source will be certainly affected because the stability of the used fluorescence material is not good.

SUMMARY OF THE INVENTION

The technical problem of the present invention to be solved is to provide a borosilicate luminescent material which have simple process, excellent quality, low cost, and can be broadly applied, and a preparing method thereof.

The technical solution to solve the technical problem in the present invention is: providing a luminescent material, the material has a chemical formula of aM₂O.bLn₂O₃.cAl₂O₃.dR₂O₃.eSiO₂.fCeO₂.gTb₂O₃ or aMO.bLn₂O₃.cAl₂O₃.dR₂O₃.eSiO₂.fCeO₂.gTb₂O₃, wherein, M is alkaline earth metal or alkali metal, Ln is selected from one or two elements of the group consisting of elements yttrium (Y) and gadolinium (Gd), R is selected from one or two elements of the group consisting of elements boron (B) and phosphorus (P), the a, b, c, d, e, f, and g are molar fractions, and 6≦a≦20, 3≦b≦12, 20≦c≦30, 32≦d≦45, 0≦e≦12, 0.01≦f≦1, and 0.05≦g≦1.5.

And, a preparing method for making a luminescent material comprises the following steps:

Step one, providing the compounds used as a source of M⁺, the compounds used as a source of Ln³⁺, the compounds used as a source of Al³⁺, the compounds used as a source of R³⁺, the compounds used as a source of silicon, the compounds used as a source of Ce³⁺, and the compounds used as a source of Tb³⁺, the stoichiometric ratio of each source compound complies with the molar ratio of elements in chemical formula of aM₂O.bLn₂O₃.cAl₂O₃.dR₂O₃.eSiO₂.fCeO₂.gTb₂O₃ or aMO.bLn₂O₃.cAl₂O₃.dR₂O₃.eSiO₂.fCeO₂.gTb₂O₃, wherein, a, b, c, d, e, f, and g are molar fractions, and 6≦a≦20, 3≦b≦12, 20≦c≦30, 32≦d≦45, 0≦e≦12, 0.01≦f≦1, and 0.05≦g≦1.5; M is alkaline earth metal or alkali metal, Ln is selected from one or two elements of the group consisting of Y and Gd, R is selected from one or two elements of the group consisting of B and P;

Step two, mixing and grinding the source compounds to get a mixture;

Step three, pre-sintering the mixture and then grinding the mixture to get a pre-sintered matter;

Step four, sintering the pre-sintered matter in reducing atmosphere and then cooling the sintered matter to get the said luminescent material.

In the preparing method of the present invention, the compounds used as a source of M⁺ are selected from one or more ingredients of the group consisting of carbonate of M⁺, nitrate of M⁺, and oxalate of M. The compounds used as a source of Ln³⁺ are selected from one or more ingredients of the group consisting of carbonate of Ln³⁺, nitrate of Ln³⁺, and oxalate of Ln³⁺. The compounds used as a source of Al³⁺ are selected from one or more ingredients of the group consisting of carbonate of Al³⁺, nitrate of Al³⁺, and oxalate of Al³⁺. The compounds used as a source of Ce³⁺ are selected from one or more ingredients of the group consisting of carbonate of Ce³⁺, nitrate of Ce³⁺, and oxalate of Ce³⁺. The compounds used as a source of Tb³⁺ are selected from one or more ingredients of the group consisting of carbonate of Tb³⁺, nitrate of Tb³⁺, and oxalate of Tb³⁺. The compounds used as a source of silicon are silicon dioxide. The compounds used as a source of R³⁺ are boric acid or phosphate.

In the preparing method of the present invention, the pre-sintering process in the said step three is carried out in air at 850° C. to 950° C. for 2 hours to 8 hours.

In the preparing method of the present invention, the sintering process in the said step four is carried out in reducing atmosphere at 750° C. to 880° C. for 2 hours to 6 hours.

In the preparing method of the present invention, the reducing atmosphere includes hydrogen (H₂) or a gas mixture of nitrogen (N₂) and H₂ or powdered carbon reducing atmosphere.

In the preparation method of the present invention, the alkaline earth metal M is at least one of calcium (Ca), strontium (Sr), and barium (Ba).

In the preparation method of the present invention, the alkali metal M is at least one of lithium (Li), sodium (Na), and potassium (K).

In the preparation method of the present invention, the optimal value ranges of a, b, c, d, e, f, and g are: 8≦a≦15, 5≦b≦10, 23≦c≦28, 35≦d≦40, 0≦e≦10, 0.05≦f≦0.8, and 0.2≦g≦1.

The borosilicate luminescent material of the present invention takes advantage of Ce ion and Tb ion which can transit energy effectively to each other nonradiatively, that is, when the luminescence center is excited, the excitation energy of one location of the illuminant transits to another location of the illuminant, or the excitation energy of the luminescence center transits to another luminescence center, with which the luminescence intensity of the borosilicate luminescent material is greatly enhanced, and, the borosilicate luminescent material is with high stability and effective photoluminescence. Especially, exited by the 350 nm to 370 nm light, the borosilicate luminescent material has a stronger luminescence intensity than that of the commercial fluorescent powders such as LaPO₄:Ce, Tb, and ZnS:Cu under their optimal excitation conditions. The preparing method for making the borosilicate luminescent material of the present invention benefits the diffuse of rare-earth active ions in borosilicate luminescent material by two-stage reaction of oxidation and reduction, and benefits the grow up of crystal of luminescent.

BRIEF DESCRIPTION OF THE DRAWINGS

Further description of the present invention will be illustrated, which combined with drawings and embodiments in the drawings.

FIG. 1 shows an emission spectrum of the borosilicate luminescent material of example 1, and emission spectrums of the commercial fluorescent powders LaPO₄:Ce, Tb, and ZnS:Cu;

FIG. 2 shows an excitation spectrum and an emission spectrum of the borosilicate luminescent material of example 2;

FIG. 3 shows an excitation spectrum and an emission spectrum of the borosilicate luminescent material of example 3;

FIG. 4 shows an excitation spectrum and an emission spectrum of the borosilicate luminescent material of example 7;

FIG. 5 shows a flow chat of preparation method of the borosilicate luminescent material.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The examples hereinafter described merely being preferred or of the invention. It will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention.

The present invention provides a borosilicate luminescent material, the borosilicate luminescent material has a chemical formula of aM₂O.bLn₂O₃.cAl₂O₃.dR₂O₃.eSiO₂.fCeO₂.gTb₂O₃, wherein, M is alkaline earth metal or alkali metal, Ln is selected from one or two elements of the group consisting of Y and Gd, R is selected from one or two elements of the group consisting of B and P; the a, b, c, d, e, f, and g are molar fractions, and 6≦a≦20, 3≦b≦12, 20≦c≦30, 32≦d≦45, 0≦e≦12, 0.01≦f≦1, and 0.05≦g≦1.5.

The alkali metal M is selected from one or more ingredients of the group consisting of Li, Na, and K. The alkaline earth metal M is selected from one or more ingredients of the group consisting of Ca, Sr, and Ba. To obtain a much stronger green light, preferably, the value ranges of the a, b, c, d, e, f, and g are: 8≦a≦15, 5≦b≦10, 23≦c≦28, 35≦d≦40, 0≦e≦10, 0.05≦f≦0.8, and 0.2≦g≦1.

The borosilicate luminescent material of the present invention takes advantage of Ce ion and Tb ion which can transit energy effectively to each other nonradiatively, that is, when the luminescence center is excited, the excitation energy of one location of the illuminant transits to another location of the illuminant, or the excitation energy of the luminescence center transits to another luminescence center, with which the luminescence intensity of the borosilicate luminescent material is greatly enhanced, and, the borosilicate luminescent material is with high stability and effective photoluminescence. Especially, exited by the 350 nm to 370 nm light, the borosilicate luminescent material has a stronger luminescence intensity than that of the commercial fluorescent powders such as LaPO₄:Ce, Tb, and ZnS:Cu under their optimal excitation peak conditions.

Referring to FIG. 5, a preparing method for making the borosilicate luminescent material includes the following steps.

SOL the compounds used as a source of M⁺, the compounds used as a source of Ln³⁺, the compounds used as a source of Al³⁺, the compounds used as a source of R³⁺, the compounds used as a source of silicon, the compounds used as a source of Ce³⁺, and the compounds used as a source of Tb³⁺ are provided. The stoichiometric ratio complies with the molar ratio of the elements in the chemical formula of aM₂O.bLn₂O₃.cAl₂O₃.dR₂O₃.eSiO₂.fCeO₂.gTb₂O₃, wherein, the a, b, c, d, e, f, and g are molar fractions, and 6≦a≦20, 3≦b≦12, 20≦c≦30, 32≦d≦45, 0≦e≦12, 0.01≦f≦1, and 0.05≦g≦1.5; M is alkaline earth metal or alkali metal, Ln is selected from one or two elements of the group consisting of Y and Gd, R is selected from one or two elements of the group consisting of B and P.

S02, mixing and grinding each source compound.

S03, pre-sintering the mixture and then grinding the mixture.

S04, sintering the pre-sintered matter in reducing atmosphere and then cooling the sintered matter to get the borosilicate luminescent material.

In step S01, the compounds used as a source of M⁺ are selected from one or more ingredients of the group consisting of carbonate of M⁺, nitrate of M⁺, and oxalate of M⁺. The compounds used as a source of Ln³⁺ are selected from one or more ingredients of the group consisting of carbonate of Ln³⁺, nitrate of Ln³⁺, and oxalate of Ln³⁺. The compounds used as a source of Al³⁺ are selected from one or more ingredients of the group consisting of carbonate of Al³⁺, nitrate of Al³⁺, and oxalate of Al³⁺. The compounds used as a source of Ce³⁺ are selected from one or more ingredients of the group consisting of carbonate of Ce³⁺, nitrate of Ce³⁺, and oxalate of Ce³⁺. The compounds used as a source of Tb³⁺ are selected from one or more ingredients of the group consisting of carbonate of Tb³⁺, nitrate of Tb³⁺, and oxalate of Tb³⁺. The compounds used as a source of silicon are silicon dioxide. The compounds used as a source of R³⁺ are boric acid or phosphate.

In step S03, the pre-sintering process is carried out in air at 850° C. to 950° C. for 2 hours to 8 hours.

In step S04, the sintering process is carried out in reducing atmosphere (the reducing atmosphere includes hydrogen (H₂), or a gas mixture of nitrogen (N₂) and H₂, or powdered carbon) at 750° C. to 880° C. for 2 hours to 6 hours according to capacity of the oven, weight of material, material kinds, and different formulations. The sintered matter is then cooled to get the borosilicate luminescent material.

The preparing method for making the borosilicate luminescent material of the present invention benefits the diffuse of rare-earth active ions in borosilicate luminescent material by two-stage reaction of oxidation and reduction, and benefits the grow up of crystal of luminescent. The matrix of the borosilicate luminescent material can absorb energy and can effectively transit the energy to the rare-earth elements of the borosilicate luminescent material, the sensitization between the rare-earth elements enhance the luminescence intensity of the borosilicate luminescent material.

Special examples are disclosed as follows to demonstrate the borosilicate luminescent materials and preparation methods of the borosilicate luminescent materials.

Example 1

5.54 gram (g) lithium carbonate, 8.75 g yttrium oxide, 13.39 g aluminum oxide, 24.8 g boric acid, 3 g silicon dioxide, 0.43 g cerium oxide, and 1.869 g terbium oxide are provided and ball grinded for 30 minutes (min). The grinded matter is sintered in air at 930° C. for 6 hours and grinded again. After that, a sintering process is carried out in reducing atmosphere of a gas mixture of N₂ and H₂ to 820° C. and kept for 6 hours. A green borosilicate luminescent powder material having a chemical formula of 15Li₂O.7.75Y₂O₃.26.25Al₂O₃.40B₂O₃.10SiO₂.0.5CeO₂.1Tb₂O₃ is obtained. Referring to FIG. 1, luminescent powder of the present invention and commercial powder LaPO₄:Ce,Tb and ZnS:Cu are excited under their optimal excitation peak conditions to get the emission spectrum. Curve 1 is an emission spectrum of the luminescent material of the present example 1, curve 2 is an emission spectrum of the commercial powder LaPO₄:Ce,Tb, and curve 3 is an emission spectrum of the commercial powder ZnS:Cu. The luminescent material of the present invention has a stronger luminescence intensity than that of the commercial powders. The equipments for testing the spectrums include a fluorescence spectrophotometer (produced by Dao-Jin company, type: RF-5301PC). The test is carried out under a condition of: low sensitivity, and 1.5 nm slit.

Example 2

7.95 g sodium carbonate, 8.75 g yttrium oxide, 13.39 g aluminum oxide, 24.8 g boric acid, 3 g silicon dioxide, 0.043 g cerium oxide, and 1.4954 g terbium oxide are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 900° C. and grinded again. After that, a sintering process is carried out in reducing atmosphere of a gas mixture of N₂ and H₂ to 880° C. and kept for 4 hours. A green borosilicate luminescent powder material having a chemical formula of 15Na₂O.7.75Y₂O₃.26.25Al₂O₃.40B₂O₃.10SiO₂.0.05CeO₂.0.8Tb₂O₃ is obtained. The luminescent material of example 2 can be excided by 363 nm light to emit blue-green light. Referring to FIG. 2, curve 4 is an excitation spectrum of the luminescent material of the present example 2, curve 5 is an emission spectrum of the luminescent material of the present example 2. The equipments for testing the spectrums include a fluorescence spectrophotometer (produced by Dao-Jin company, type: RF-5301PC). The test is carried out under a condition of: low sensitivity, and 1.5 nm slit.

Example 3

7.95 g sodium carbonate, 8.75 g yttrium oxide, 13.39 g aluminum oxide, 24.8 g boric acid, 3 g silicon dioxide, 0.43 g cerium oxide, and 1.6823 g terbium oxide are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 920° C. and then grinded again. After that, a sintering process is carried out in reducing atmosphere of H₂ to 800° C. and kept for 2 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 15Na₂O.7.75Y₂O₃.26.25Al₂O₃.40B₂O₃.10SiO₂.0.5CeO₂.0.9Tb₂O₃ is obtained. The luminescent material of example 3 can be excided by 363 nm light to emit blue-green light. Referring to FIG. 3, curve 6 is an excitation spectrum of the luminescent material of the present example 3, curve 7 is an emission spectrum of the luminescent material of the present example 2. The equipments for testing the spectrums include a fluorescence spectrophotometer (produced by Dao-Jin company, type: RF-5301PC). The test is carried out under a condition of: low sensitivity, and 1.5 nm slit.

Example 4

3.18 g sodium carbonate, 21.75 g yttrium oxide, 15.3 g aluminum oxide, 27.9 g boric acid, 2.1 g silicon dioxide, 0.86 g cerium oxide, and 2.804 g terbium oxide are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 880° C. for 8 hours and grinded again. After that, a sintering process is carried out in reducing atmosphere of powdered carbon to 750° C. and kept for 6 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 6Na₂O.7.75Gd₂O₃.30Al₂O₃.45B₂O₃.7SiO₂.1CeO₂.1.5Tb₂O₃ is obtained.

Example 5

16.62 g potassium oxalate, 13.78 g yttrium nitrate, 42.6 g aluminum nitrate, 27.9 g boric acid, 3 g silicon dioxide, 0.0115 g cerium carbonate, and 0.1245 g terbium carbonate are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 900° C. for 8 hours and grinded again. After that, a sintering process is carried out in reducing atmosphere of powered carbon to 800° C. and kept for 5 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 6K₂O.5Y₂O₃.20Al₂O₃.45B₂O₃.10SiO₂.0.01CeO₂.0.05Tb₂O₃ is obtained.

Example 6

17 g sodium nitrate, 5.36 g yttrium carbonate, 23.4 g aluminum carbonate, 31.95 g phosphorous pentoxide, 3.6 g silicon dioxide, 1.304 g cerium nitrate, and 2.5875 g terbium nitrate are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 850° C. for 8 hours and then grinded again. After that, a sintering process is carried out in reducing atmosphere of a gas mixture of N₂ and H₂ to 750° C. and kept for 4 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 20Na₂O.3Y₂O₃.20Al₂O₃.45P₂O₃.12SiO₂.0.8CeO₂.1.5Tb₂O₃ is obtained.

Example 7

6.17 g lithium carbonate, 9.709 g yttrium oxide, 14.892 g aluminum oxide, 26.64 g boric acid, 0.473 g cerium oxide, and 2.056 g terbium oxide are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 930° C. for 4 hours and then grinded again. After that, a sintering process is carried out in reducing atmosphere of a gas mixture of N₂ and H₂ to 790° C. and kept for 2 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 16.7Li₂O.8.6Y₂O₃.29.2Al₂O₃.44.4B₂O₃O.0.55CeO₂.1.1Tb₂O₃ is obtained. The luminescent material of example 7 can be excided by 367 nm light to emit blue-green light. Referring to FIG. 4, curve 8 is an excitation spectrum of the luminescent material of the present example 7, curve 9 is an emission spectrum of the luminescent material of the present example 7. The equipments for testing the spectrums include a fluorescence spectrophotometer (produced by Dao-Jin company, type: RF-5301PC). The test is carried out under a condition of: low sensitivity, and 1.5 nm slit.

Example 8

11.07 g strontium carbonate, 17.13 g yttrium oxalate, 41.73 g aluminum oxalate, 28.4 g phosphorous pentoxide, 3 g silicon dioxide, 0.6804 g cerium oxalate, and 2.91 g terbium oxalate are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 850° C. for 8 hours and then grinded again. After that, a sintering process is carried out in reducing atmosphere of a gas mixture of N₂ and H₂ to 760° C. and kept for 4 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 15SrO.7.75Y₂O₃.26.25Al₂O₃.40P₂O₃.10SiO₂.0.5CeO₂.1Tb₂O₃ is obtained.

Example 9

15.87 g strontium nitrate, 19.16 g gadolinium carbonate, 30.7 g aluminum carbonate, 28.4 g phosphorous pentoxide, 3 g silicon dioxide, 0.92 g cerium carbonate, and 2.987 g terbium carbonate are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 850° C. for 8 hours and grinded again. After that, a sintering process is carried out in reducing atmosphere of H₂ to 780° C. and kept for 6 hours. A green borosilicate luminescent powder material 15SrO.7.75Gd₂O₃.26.25Al₂O₃.40P₂O₃.10SiO₂.0.8CeO₂.1.2Tb₂O₃ is obtained.

Example 10

10.2 g lithium oxalate, 13.78 g yttrium nitrate, 23.4 g aluminum carbonate, 31.95 g phosphorous pentoxide, 3 g silicon dioxide, 0.086 g cerium oxide, and 1.308 g terbium oxide are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 850° C. for 8 hours and then grinded again. After that, a sintering process is carried out in reducing atmosphere of H₂ to 780° C. and kept for 8 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 20Li₂O.5Y₂O₃.20Al₂O₃.45P₂O₃.10SiO₂.0.1CeO₂.0.7Tb₂O₃ is obtained.

Example 11

12.3 g calcium nitrate, 22.42 g gadolinium oxalate, 41.74 g aluminum oxalate, 24.8 g boric acid, 3 g silicon dioxide, 1.63 g cerium nitrate, and 1.869 g terbium oxide are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 880° C. for 6 hours and then grinded again. After that, a sintering process is carried out in reducing atmosphere of H₂ to 780° C. and kept for 7 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 15CaO.7.75Gd₂O₃.26.25Al₂O₃.40B₂O₃.10SiO₂.1CeO₂.1Tb₂O₃ is obtained.

Example 12

20.277 g barium oxalate, 14.312 g yttrium carbonate, 34.98 g aluminum oxalate, 24.8 g boric acid, 3 g silicon dioxide, 1.035 g cerium carbonate, and 2.803 g terbium oxide are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 880° C. for 8 hours and then grinded again. After that, a sintering process is carried out in reducing atmosphere of H₂ to 780° C. and kept for 6 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 18BaO.8Y₂O₃.22Al₂O₃.40B₂O₃.10SiO₂.0.9CeO₂.1.5Tb₂O₃ is obtained.

Example 13

12.8 g calcium oxalate, 29.67 g gadolinium carbonate, 59.64 g aluminum nitrate, 24.8 g boric acid, 0.688 g cerium oxide, and 2.43 g terbium oxide are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 850° C. for 8 hours and then grinded again. After that, a sintering process is carried out in reducing atmosphere of a gas mixture of N₂ and H₂ to 800° C. and kept for 6 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 20CaO.12Gd₂O₃.28Al₂O₃.40B₂O₃.0.8CeO₂.1.3Tb₂O₃ is obtained.

Example 14

7.5 g calcium carbonate, 14.05 g gadolinium oxide, 13.39 g aluminum oxide, 28.4 g phosphorous pentoxide, 3 g silicon dioxide, 0.258 g cerium oxide, and 1.869 g terbium oxide are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 850° C. for 8 hours and grinded again. After that, a sintering process is carried out in reducing atmosphere of a gas mixture of N₂ and H₂ to 760° C. and kept for 6 hours. A green borosilicate luminescent powder material 15CaO.7.75Gd₂O₃.26.25Al₂O₃.40P₂O₃.10SiO₂.0.3CeO₂.1Tb₂O₃ is obtained.

Example 15

11.1 g sodium oxalate, 12.36 g gadolinium carbonate, 10.2 g aluminum oxide, 27.9 g boric acid, 3 g silicon dioxide, 0.086 g cerium oxide, and 1.75 g terbium carbonate are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 850° C. for 8 hours and then grinded again. After that, a sintering process is carried out in reducing atmosphere of H₂ to 780° C. and kept for 6 hours. As such, a borosilicate luminescent material having a chemical formula of 20Na₂O.5Gd₂O₃.20Al₂O₃.45B₂O₃.10SiO₂.0.1CeO₂.0.7Tb₂O₃ is obtained.

Example 16

15.15 g potassium nitrate, 19.16 g gadolinium carbonate, 13.39 g aluminum oxide, 24.8 g boric acid, 3 g silicon dioxide, 0.258 g cerium oxide, and 2.485 g terbium carbonate are provided and ball grinded for 30 min. The grinded matter is sintered in atmosphere at 850° C. for 8 hours and then grinded again. After that, a sintering process is carried out in reducing atmosphere of H₂ to 750° C. and kept for 6 hours. As such, a green borosilicate luminescent powder material having a chemical formula of 15K₂O.7.75Gd₂O₃.26.25Al₂O₃.40B₂O₃.10SiO₂.0.3CeO₂.1Tb₂O₃ is obtained.

It is believed that the present invention and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its advantages, the examples hereinbefore described merely being preferred or present invention of the disclosure. 

What is claimed is:
 1. A luminescent material, which has a chemical formula of aM₂O.bLn₂O₃.cAl₂O₃.dR₂O₃.eSiO₂.fCeO₂.gTb₂O₃ or aMO.bLn₂O₃.cAl₂O₃.dR₂O₃.eSiO₂.fCeO₂.gTb₂O₃, wherein, M is alkaline earth metal or alkali metal, Ln is selected from one or two elements of the group consisting of yttrium and gadolinium, R is selected from one or two elements of the group consisting of boron and phosphorus, the a, b, c, d, e, f, and g are molar fractions, and 6≦a≦20, 3≦b≦12, 20≦c≦30, 32≦d≦45, 0≦e≦12, 0.01≦f≦1, and 0.05≦g≦1.5.
 2. The luminescent material according to claim 1, wherein said alkali metal M is selected from one or more ingredients of the group consisting of lithium, sodium, and potassium.
 3. The luminescent materials according to claim 1, wherein said alkaline earth metal M is selected from one or more ingredients of the group consisting of calcium, strontium, and barium.
 4. The luminescent materials according to claim 1, wherein the value ranges of the a, b, c, d, e, f, and g are: 8≦a≦15, 5≦b≦10, 23≦c≦28, 35≦d≦40, 0≦e≦10, 0.05≦f≦0.8, and 0.2≦g≦1.
 5. A preparing method for making a luminescent material, comprising the following steps of: Step one, providing the compounds used as a source of W, the compounds used as a source of Ln³⁺, the compounds used as a source of Al³⁺, the compounds used as a source of R³⁺, the compounds used as a source of silicon, the compounds used as a source of Ce³⁺, and the compounds used as a source of Tb³⁺, the stoichiometric ratio of each source compound complies with the molar ratio of the elements in the chemical formula of aM₂O.bLn₂O₃.cAl₂O₃.dR₂O₃.eSiO₂.fCeO₂.gTb₂O₃ or aMO.bLn₂O₃.cAl₂O₃.dR₂O₃.eSiO₂.fCeO₂.gTb₂O₃, wherein, the a, b, c, d, e, f, and g are molar fractions, and 6≦a≦20, 3≦b≦12, 20≦c≦30, 32≦d≦45, 0≦e≦12, 0.01≦f≦1, and 0.05≦g≦1.5; M is alkaline earth metal or alkali metal, Ln is selected from one or two elements of the group consisting of yttrium and gadolinium, R is selected from one or two elements of the group consisting of boron and phosphorus; Step two, mixing and grinding the source compounds to get a mixture; Step three, pre-sintering the mixture and then grinding the mixture to get a pre-sintered matter; Step four, sintering the pre-sintered matter in reducing atmosphere and then cooling the sintered matter to get the said luminescent material.
 6. The preparing method for making a luminescent material according to claim 5, wherein the compounds used as a source of M⁺ is selected from one or more ingredients of the group consisting of carbonate of M⁺, nitrate of M⁺, and oxalate of M⁺, the compounds used as a source of Ln³⁺ is selected from one or more ingredients of the group consisting of carbonate of Ln³⁺, nitrate of Ln³⁺, and oxalate of Ln³⁺, the compounds used as a source of Al³⁺ is selected from one or more ingredients of the group consisting of carbonate of Al³⁺, nitrate of Al³⁺, and oxalate of Al³⁺, the compounds used as a source of Ce³⁺ is selected from one or more ingredients of the group consisting of carbonate of Ce³⁺, nitrate of Ce³⁺, and oxalate of Ce³⁺, the compounds used as a source of Tb³⁺ is selected from one or more ingredients of the group consisting of carbonate of Tb³⁺, nitrate of Tb³⁺, and oxalate of Tb³⁺, the compounds used as a source of silicon is silicon dioxide, the compounds used as a source of R³⁺ is boric acid or phosphate.
 7. The preparing method for making a luminescent material according to claim 5, wherein in step three, the pre-sintering process is carried out in air at 850° C. to 950° C. for 2 hours to 8 hours.
 8. The preparing method for making a luminescent material according to claim 5, wherein in step four, the sintering process is carried out in reducing atmosphere at 750° C. to 880° C. for 2 hours to 6 hours.
 9. The preparing method for making a luminescent material according to claim 8, wherein the reducing atmosphere is hydrogen, carbon monoxide, or a gas mixture of nitrogen and hydrogen.
 10. The preparing method for making a luminescent material according to claim 5, wherein said alkaline earth metal M is at least one of calcium, strontium, and barium.
 11. The preparing method for making a luminescent material according to claim 5, wherein said alkali metal M is at least one of lithium, sodium, and potassium.
 12. The preparation methods for making a luminescent material according to claim 5, wherein the value ranges of the a, b, c, d, e, f, and g are: 8≦a≦15, 5≦b≦10, 23≦c≦28, 35≦d≦40, 0≦e≦10, 0.05≦f≦0.8, and 0.2≦g≦1. 